Tocopherol Fate in Plasma and Liver of Streptozotocin-Treated Rats that Orally Received Antioxidants and Spirulina Extracts

Streptozotocin-induced diabetic rats constitute a model of oxidative stress, and vitamin E continues to be a topic of speculation in this area. On the other hand, marine extracts, particularly microalgae extracts obtained with environmentally clean technologies and which demonstrate antioxidant activity in vitro, are a potential source of in vivo antioxidant defense. We have studied the alpha-tocopherol content in the plasma and liver of diabetic rats after 7 and 14 days under the condition, and before and after the treatment with vitamin E and C, as well as with different Spirulina extracts, as compared with the corresponding controls. The improvement of analytical methodology related to the determination of alpha-tocopherol in the plasma and liver of rats was also considered. To do this, a method previously developed for plasma, employing a single extraction step, was adapted and validated for liver after minor modifications. Moreover, stability of alpha-tocopherol in plasma of diabetic and control animals was compared in different storage conditions. Results showed that diabetic plasma strongly influences stability of alpha-tocopherol, even at -20 degrees C, but samples are stable for at least one year at -80 degrees C. Finally, regarding supplementation, results indicate that supplementation with alpha-tocopherol increases stored alpha-tocopherol in liver, but not in plasma, but this availability is strongly dependent on the stage of diabetes of the animal. Extracts of Spirulina platensis, despite showing antioxidant activity in vitro, increased alpha-tocopherol concentration in neither plasma nor liver.